— Pennsylvania Gov. Tom Wolf's chief of staff, Katie McGinty, isn't ruling out a run for the U.S. Senate after national Democrats have urged her to consider entering the race.

It's a field that narrowed this week when Allentown Mayor Ed Pawlowski suspended his Senate bid, amid a federal investigation into the city's contracting practices. That leaves one Democrat — retired Navy admiral and former congressman Joe Sestak — in the race to unseat Republican Sen. Pat Toomey.

But the candidate field is anything but final, with key Democrats confirming that McGinty has had conversations since May with top party officials in Washington and the Democratic Senatorial Campaign Committee. It was unclear whether there have been any new talks since Pawlowski pulled out Monday.

The former state environmental protection secretary and former -aide to Vice President Al Gore ran against Wolf in the 2014 primary. She then teamed up with him, leading Wolf's Fresh Start PAC for the remainder of the campaign.

Political observers say she exited the governor's race with a positive reputation. However, her departure from the Wolf administration would be an unusually quick turnaround for a top aide and one that could be hampered by the still-unfinished state budget.

It would be difficult for McGinty to leave her post and begin setting up a Senate campaign before next year's spending plan is completed, said G. Terry Madonna, a political scientist at Franklin & Marshall College.

Her former campaign manager, Mike Mikus, said her attention is on the budget, which was supposed to be wrapped up by June 30.

Former Gov. Ed Rendell, who appointed McGinty as his DEP chief, told the Associated Press that he thinks McGinty would be a "terrific candidate." However, he said she would need to leave her post in the coming weeks and that he doesn't think she'll run.

Other Democrats described her as still considering the race after encouragement from national party leaders.

McGinty was an unusual pick as Wolf's chief of staff, a role that typically is not held by someone who has been an office-seeker. In that position, she's used her campaign skills as she carves out a visible role that has included numerous public appearances.

"She's been the most omnipresent chief of staff that I've known," Madonna said.

If she decides to run, one primary task will be fundraising: Sestak had about $1.7 million on hand at the end of March. Fundraising reports for the last three months are due next week.

She'd be likely to get significant assistance from party leaders, who have a fraught relationship with Sestak.

He's viewed as a tenacious campaigner and has been traveling the state almost continuously since his narrow loss to Toomey in 2010.

Still, party leaders have not been shy about seeking an alternative candidate, pressing Montgomery County Commissioner Josh Shapiro to enter the contest until he publicly ruled out a bid in May.

Little is known publicly about why FBI agents searched Allentown City Hall last Thursday. City officials have said they believe it was related to contracting based on the nature of the documents seized. No inventory of what was removed has been made public, nor has anyone been named a target.

Pawlowski said in a statement Monday he was suspending his campaign to "fully focus on assisting" in the federal investigation. He said he'd reevaluate getting back into the race "once we have a more clear picture of any potential concerns with Allentown's government."

A Democratic Senatorial Campaign Committee spokesman declined to comment about discussions with McGinty.

Philadelphia congressman Bob Brady told the Philadelphia Inquirer that he'd back McGinty over Sestak, continuing his criticism of the former Delaware County congressman.

The intraparty turmoil gives additional fodder for Toomey — who has a hefty campaign account and no primary opponent — to use against his lead challenger. His campaign swiftly sent out a release highlighting Brady's comments Wednesday.